Components & data¶

The curated open component database, the Component record, the helpers that turn component names into the constant arrays the rest of the engine consumes, and the physical constants.

Components¶

components ¶

Pure-component model and a curated database of open reference constants.

A Component is an immutable bundle of the constants Fugacio needs to evaluate equations of state, ideal-gas properties, and saturation pressures for one chemical species. The values bundled in DATABASE are textbook reference data drawn from open sources:

critical constants and acentric factors: Poling, Prausnitz & O'Connell, The Properties of Gases and Liquids (5^th ed.), Appendix A;
ideal-gas heat capacities: Smith, Van Ness & Abbott, Introduction to Chemical Engineering Thermodynamics (7^th ed.), Table C.1, in the form Cp/R = a + b*T + c*T**2 + d/T**2;
Antoine vapour-pressure constants: NIST Chemistry WebBook, in the form log10(P/bar) = a - b / (T/K + c).

Component instances are deliberately static Python objects (not JAX pytrees): the differentiable numerical kernels in fugacio.thermo operate on plain arrays, which you extract with component_arrays. That keeps gradients flowing with respect to the physical parameters themselves (useful for parameter estimation) without entangling autodiff with database bookkeeping.

Classes:

Name	Description
`AntoineCoeffs`	Antoine vapour-pressure constants in NIST form.
`CpIdeal`	Ideal-gas heat-capacity correlation `Cp/R = a + bT + cT2 + d/T2 + eT*3`.
`Component`	Immutable pure-component constant record (SI units, except molar mass).

Functions:

Name	Description
`get`	Return the `Component` for `name` (case-insensitive).
`names`	Return the sorted list of component names in the database.
`component_arrays`	Stack the core EOS constants of several components into JAX arrays.

AntoineCoeffs `dataclass` ¶

AntoineCoeffs(
    a: float, b: float, c: float, t_min: float, t_max: float
)

Antoine vapour-pressure constants in NIST form.

log10(P/bar) = a - b / (T/K + c), valid on [t_min, t_max] kelvin.

CpIdeal `dataclass` ¶

CpIdeal(
    a: float,
    b: float,
    c: float,
    d: float,
    e: float = 0.0,
    t_min: float = 0.0,
    t_max: float = float("inf"),
)

Ideal-gas heat-capacity correlation Cp/R = a + b*T + c*T**2 + d/T**2 + e*T**3.

The a, b, c, d form is the one tabulated by Smith, Van Ness & Abbott (at most three coefficients non-zero per species, e = 0). The extra cubic term e lets the same dataclass also hold Joback-style estimates (a + b*T + c*T**2 + e*T**3), keeping a single ideal-gas integrator for both. t_min and t_max bound the fitted temperature range in kelvin.

Component `dataclass` ¶

Component(
    name: str,
    formula: str,
    cas: str | None,
    mw: float,
    tc: float,
    pc: float,
    omega: float,
    tb: float | None = None,
    vc: float | None = None,
    zc: float | None = None,
    antoine: AntoineCoeffs | None = None,
    cp_ig: CpIdeal | None = None,
    hform_ig: float | None = None,
    gform_ig: float | None = None,
    dipole: float | None = None,
    zra: float | None = None,
)

Immutable pure-component constant record (SI units, except molar mass).

Attributes:

Name	Type	Description
`name`	`str`	Canonical lower-case identifier (the database key).
`formula`	`str`	Molecular formula, e.g. `"C2H6O"`.
`cas`	`str \| None`	CAS registry number as a string, or `None` if unassigned here.
`mw`	`float`	Molar mass in g/mol.
`tc`	`float`	Critical temperature in K.
`pc`	`float`	Critical pressure in Pa.
`omega`	`float`	Pitzer acentric factor (dimensionless).
`tb`	`float \| None`	Normal boiling point in K, or `None`.
`vc`	`float \| None`	Critical molar volume in m^3/mol, or `None`.
`zc`	`float \| None`	Critical compressibility factor, or `None`.
`antoine`	`AntoineCoeffs \| None`	`AntoineCoeffs`, or `None` if not tabulated.
`cp_ig`	`CpIdeal \| None`	`CpIdeal`, or `None` if not tabulated.
`hform_ig`	`float \| None`	Standard ideal-gas enthalpy of formation (J/mol at 298.15 K).
`gform_ig`	`float \| None`	Standard ideal-gas Gibbs energy of formation (J/mol at 298.15 K).
`dipole`	`float \| None`	Gas-phase dipole moment in debye, or `None` if not tabulated.
`zra`	`float \| None`	Spencer-Danner Rackett compressibility `Z_RA`, or `None`.

get ¶

get(name: str) -> Component

Return the Component for name (case-insensitive).

Raises:

Type	Description
`KeyError`	if `name` is not present in `DATABASE`.

names ¶

names() -> list[str]

Return the sorted list of component names in the database.

component_arrays ¶

component_arrays(
    components: list[str] | list[Component],
) -> dict[str, Array]

Stack the core EOS constants of several components into JAX arrays.

Parameters:

Name	Type	Description	Default
`components`	`list[str] \| list[Component]`	A list of component names or `Component` objects.	required

Returns:

Type	Description
`dict[str, Array]`	A dict with keys `"tc"`, `"pc"`, `"omega"` and `"mw"` mapping to
`dict[str, Array]`	1-D arrays aligned with the input order, ready to feed the equation-of-
`dict[str, Array]`	state kernels.

Binary interaction data¶

Lookups that pull stored binary-interaction parameters (cubic-EOS kij, NRTL, and UNIQUAC) out of the database for a set of components.

data ¶

Curated parameter lookups: UNIQUAC r/q and binary NRTL / UNIQUAC.

This is the convenience layer over the generated tables in fugacio.thermo._binary_params. It turns component names into ready, fully populated NRTL / UNIQUAC model objects, handling the pair-ordering bookkeeping (the tables are keyed by alphabetically sorted name pairs) and assembling the n x n interaction matrices.

Pairs absent from the curated set default to athermal interaction (b = 0, so gamma -> 1 for that pair) unless strict=True is requested, in which case a missing pair raises. For systems with no curated parameters at all, fall back to predictive UNIFAC (fugacio.thermo.groupcontrib.unifac_activity) or fit parameters from data with fugacio.thermo.regression.

Functions:

Name	Description
`nrtl_params`	Oriented binary NRTL params `(b_ij, b_ji, alpha_ij)` or `None` if absent.
`uniquac_params`	Oriented binary UNIQUAC params `(b_ij, b_ji)` or `None` if absent.
`pr_kij`	Curated Peng-Robinson binary interaction coefficient `k_ij` or `None`.
`kij_from_database`	Assemble the symmetric Peng-Robinson `k_ij` matrix from curated pairs.
`uniquac_rq`	Return the UNIQUAC `(r, q)` arrays for named components.
`nrtl_from_database`	Build an `NRTL` model for `components` from curated binaries.
`uniquac_from_database`	Build a `UNIQUAC` model for `components` from curated data.
`has_nrtl`	Whether every binary pair in `components` has curated NRTL parameters.
`has_uniquac`	Whether `components` have curated UNIQUAC `r`/`q` and all pair params.

nrtl_params ¶

nrtl_params(
    name_i: str, name_j: str
) -> tuple[float, float, float] | None

Oriented binary NRTL params (b_ij, b_ji, alpha_ij) or None if absent.

tau_ij = b_ij / T. Lookup is order-insensitive; the result is oriented so that b_ij is the coefficient acting on the i -> j direction.

uniquac_params ¶

uniquac_params(
    name_i: str, name_j: str
) -> tuple[float, float] | None

Oriented binary UNIQUAC params (b_ij, b_ji) or None if absent.

tau_ij = exp(b_ij / T); lookup is order-insensitive (see nrtl_params).

pr_kij ¶

pr_kij(name_i: str, name_j: str) -> float | None

Curated Peng-Robinson binary interaction coefficient k_ij or None.

Order-insensitive (k_ij is symmetric for the standard one-fluid rule).

kij_from_database ¶

kij_from_database(components: list[str]) -> Array

Assemble the symmetric Peng-Robinson k_ij matrix from curated pairs.

Pairs without a curated value default to 0 (ideal van der Waals mixing). The result is an (n, n) array suitable for fugacio.thermo.eos_model / fugacio.sim.eos_model_for.

uniquac_rq ¶

uniquac_rq(components: list[str]) -> tuple[Array, Array]

Return the UNIQUAC (r, q) arrays for named components.

Raises:

Type	Description
`KeyError`	if any component lacks curated `r`/`q` data.

nrtl_from_database ¶

nrtl_from_database(
    components: list[str],
    *,
    strict: bool = False,
    alpha_default: float = 0.3,
) -> NRTL

Build an NRTL model for components from curated binaries.

Parameters:

Name	Type	Description	Default
`components`	`list[str]`	Component names (any length `>= 2`).	required
`strict`	`bool`	If `True`, raise when a pair has no curated parameters; otherwise that pair defaults to athermal (`b = 0`).	`False`
`alpha_default`	`float`	Non-randomness used for pairs without curated parameters.	`0.3`

Returns:

Type	Description
`NRTL`	A fully populated `NRTL` whose `b` and `alpha` matrices are the
`NRTL`	curated coefficients (`a = e = 0`).

uniquac_from_database ¶

uniquac_from_database(
    components: list[str], *, strict: bool = False
) -> UNIQUAC

Build a UNIQUAC model for components from curated data.

Uses curated r/q and binary b coefficients. Pairs without data default to b = 0 (tau = 1) unless strict=True.

Raises:

Type	Description
`KeyError`	if any component lacks `r`/`q` (always), or any pair lacks interaction parameters (only when `strict=True`).

has_nrtl ¶

has_nrtl(components: list[str]) -> bool

Whether every binary pair in components has curated NRTL parameters.

has_uniquac ¶

has_uniquac(components: list[str]) -> bool

Whether components have curated UNIQUAC r/q and all pair params.

Constants¶

constants ¶

Physical constants and unit conversions used across fugacio.thermo.

Fugacio works in SI internally:

temperature T in kelvin (K),
pressure P in pascal (Pa),
amount in mole (mol),
molar energy in joule per mole (J/mol),
molar volume in cubic metre per mole (m^3/mol).

Molar mass is the one deliberate exception: it is stored in the conventional gram-per-mole (g/mol), matching how component data are tabulated. Convert to kg/mol with G_PER_MOL_TO_KG_PER_MOL when you need mass in SI.

The numerical values follow the 2018 CODATA recommended values, so they match the constants used by the open reference codes Fugacio is graded against.

Functions:

Name	Description
`celsius_to_kelvin`	Convert a temperature from degrees Celsius to kelvin.
`kelvin_to_celsius`	Convert a temperature from kelvin to degrees Celsius.

celsius_to_kelvin ¶

celsius_to_kelvin(t_celsius: float) -> float

Convert a temperature from degrees Celsius to kelvin.

kelvin_to_celsius ¶

kelvin_to_celsius(t_kelvin: float) -> float

Convert a temperature from kelvin to degrees Celsius.

Components & data¶

Components¶

components ¶

AntoineCoeffs dataclass ¶

CpIdeal dataclass ¶

Component dataclass ¶

get ¶

names ¶

component_arrays ¶

Binary interaction data¶

data ¶

nrtl_params ¶

uniquac_params ¶

pr_kij ¶

kij_from_database ¶

uniquac_rq ¶

nrtl_from_database ¶

uniquac_from_database ¶

has_nrtl ¶

has_uniquac ¶

Constants¶

constants ¶

celsius_to_kelvin ¶

kelvin_to_celsius ¶

AntoineCoeffs `dataclass` ¶

CpIdeal `dataclass` ¶

Component `dataclass` ¶